constexpress=require("express");constapp=express();app.get("/",(req,res)=>{console.log("Hello world received a request.");consttarget=process.env.TARGET||"World";res.send(`Hello ${target}!`);});constport=process.env.PORT||8080;app.listen(port,()=>{console.log("Hello world listening on port",port);});

Modify the package.json file to add a start command to the scripts section:

In your project directory, create a file named Dockerfile and copy the code
block below into it. For detailed instructions on dockerizing a Node.js app,
see
Dockerizing a Node.js web app.

# Use the official Node.js 12 image.# https://hub.docker.com/_/node FROM node:12# Create and change to the app directory. WORKDIR /usr/src/app# Copy application dependency manifests to the container image.# A wildcard is used to ensure both package.json AND package-lock.json are copied.# Copying this separately prevents re-running npm install on every code change. COPY package*.json ./# Install production dependencies. RUN npm install --only=production# Copy local code to the container image. COPY . .# Run the web service on container startup. CMD ["npm", "start"]

Create a .dockerignore file to ensure that any files related to a local
build do not affect the container that you build for deployment.

Dockerfile
README.md
node_modules
npm-debug.log

Create a new file, service.yaml and copy the following service definition
into the file. Make sure to replace {username} with your Docker Hub
username.

After the build has completed and the container is pushed to docker hub, you
can deploy the app into your cluster. Ensure that the container image value
in service.yaml matches the container you built in the previous step. Apply
the configuration using kubectl:

kubectl apply --filename service.yaml

Now that your service is created, Knative will perform the following steps:

Automatically scale your pods up and down (including to zero active pods).

To find the IP address for your service, use these commands to get the
ingress IP for your cluster. If your cluster is new, it may take sometime for
the service to get asssigned an external IP address.

# In Knative 0.2.x and prior versions, the `knative-ingressgateway` service was used instead of `istio-ingressgateway`.INGRESSGATEWAY=knative-ingressgateway
# The use of `knative-ingressgateway` is deprecated in Knative v0.3.x.# Use `istio-ingressgateway` instead, since `knative-ingressgateway`# will be removed in Knative v0.4.if kubectl get configmap config-istio -n knative-serving &> /dev/null;thenINGRESSGATEWAY=istio-ingressgateway
fi
kubectl get svc $INGRESSGATEWAY --namespace istio-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
xxxxxxx-ingressgateway LoadBalancer 10.23.247.74 35.203.155.229 80:32380/TCP,443:32390/TCP,32400:32400/TCP 2d